A sidetone is a portion of a sound signal which is fed from a telephone's mouthpiece (i.e., microphone) back to an earpiece (i.e., loudspeaker). For the most part, all wired phones generate such a sidetone. Sidetones have a significant effect on the perceived quality of a telephone connection. When a person using a telephone hears a sidetone it gives her a sense of confidence that her phone and the network she is speaking “over” are working properly.
In an ideal case, a sidetone signal consists of the voice of the person who is speaking into the telephone or the like. However, when background noise is present the sidetone signal also includes background sounds.
For wireless or mobile telephones, sidetones become more problematic because they are often used in noisy environments (e.g., noise from cars, trains, airports, streets). For the sake of simplicity, and to avoid background noise problems, many manufacturers have decided to build wireless phones that provide no sidetone signals, thereby accepting the degradation in quality which occurs in noise-free environments. It is desirable, however, to generate sidetone signals that do not negatively impact a telephone conversation in a noisy environment.
Some have attempted to reduce sidetone noise by incorporating circuits which eliminate the sidetone altogether when a listener does not speak into a telephone within a certain timeframe. This technique is confusing to some users because the sounds coming from such a telephone's earpiece appear to cut in and out. Other techniques have been developed but they all have their drawbacks.
Accordingly, it is a desire of the present invention to provide for improved techniques for reducing sidetone noise levels.
Other desires of the present invention will become apparent from the drawings, detailed description of the invention and claims which follow.